Boundary problems in stratigraphy involve the challenges in precisely defining, correlating, and interpreting the limits between successive geological time or rock units. These difficulties arise from geological complexities like unconformities, diachroneity of facies, or a scarcity of diagnostic fossils. An ideal boundary should be globally distinct and correlatable, a condition often hard to achieve.

The Cretaceous/Palaeogene (K/Pg) boundary, formerly K/T, marks one of Earth's largest mass extinctions approximately 66 million years ago, ending the Mesozoic Era. The core problem is establishing the exact cause and timing of the extinction relative to major geological events. Globally, the K/Pg boundary is characterized by a distinct iridium anomaly, shocked quartz, and microtektites in a specific clay layer, widely interpreted as evidence of a massive asteroid impact (Chicxulub). This event led to the demise of non-avian dinosaurs and significant marine and terrestrial species.

In India, the K/Pg boundary problem is complexly intertwined with the Deccan Volcanic Province (Deccan Traps), one of Earth's largest flood basalt events. These eruptions spanned the K/Pg boundary, covering vast areas of west-central India. The debate revolves around whether Deccan volcanism, through atmospheric changes, significantly contributed to the mass extinction, or if it was merely coincidental with the asteroid impact. Some research suggests a critical phase of Deccan volcanism directly coincided with the Chicxulub impact, implying a potential causal link.

Indian geological sections offer crucial insights. In marine areas like the Ariyalur and Trichinopoly formations of Tamil Nadu, K/Pg boundary sections with iridium anomalies are identifiable, often exhibiting transitional faunal changes. However, within the Deccan region itself, the voluminous basaltic flows frequently obscure or truncate any sedimentary record of the K/Pg event, complicating precise correlation. India's geological record thus remains vital for understanding the interplay between impact and volcanism during this pivotal extinction.